1. Field of the Invention
The invention relates to regulated power supply circuitry for low duty cycle, high voltage load pulsing and, more particularly, to such devices of the energy conservative type which also incorporate a regulating function.
2. Description of the Prior Art
As is well known in the prior art, the typical microwave thermionic power device, such as the magnetron, amplitron, etc., requires high voltage pulsing. The so-called line-type modulator is a well known device used in connection with a high voltage switch (such as the hydrogen thyratron, for example) to couple a high voltage pulse, usually through a suitable pulse transformer to the microwave power tube which is operative as a microwave oscillator or amplifier. Such devices are desicrbed in the text, Radar Handbook, by Merill I. Skolnik (McGraw-Hill Book Company, 1970), particularly in Chapter 7 thereof.
The process of disposing of excess charging choke (inductor) energy is sometimes referred to as de-Q-ing. The aforementioned Radar Handbook describes this process in its Chapter 7 and illustrates two forms of dissipative-type regulators in FIG. 49. Those devices are based on the dissipation of excess charging choke (inductor) energy in a high-current-rated vacuum tube shunted across the charging choke and controlled to conduct at the appropriate time corresponding to charging of the pulse-forming network to the desired point. The prime disadvantage of such systems is that, at high line voltages, up to 30% of the input power is wasted ultimately as heat.
The same chapter of the Radar Handbook text also shows, in FIG. 50, two forms of resonant-charging regulators which are of the energy-conservative type. In these, the secondary of the charging inductor is enabled (i.e., connected directly or through a diode) to feed back to the power supply filter/storage capacitor. In one form of FIG. 50 of the Handbook reference, a series triode at high voltage interrupts the pulse-forming network charging cycle, leaving the charging choke energy to automatically fly back and, through the secondary of the charging inductor, dump its residual energy into the power supply filter/storage capacitor.
In the other form shown in that reference, a solid state switch, such as a thyristor, etc., closes the circuit between the charging conductor secondary and the power supply/filter storage capacitor at the time the pulse-forming network predetermined charge point is reached.
It will be seen from the foregoing that the principle of residual charging inductor energy recovery is, of itself, known. However, in the form of FIG. 50(a) of the reference, a high voltage series triode is required. The somewhat simpler form of FIG. 50(b) of the reference involves the use of a thyristor switch which is subject to the high common mode voltage of the power supply through the secondary charging inductor. A second transformer in that circuit serves only to couple-in the thyristor trigger independently of the common mode voltage but serves no function in isolating this thyristor from the high common mode voltage.
The manner in which the present invention deals with the disadvantages of the prior art in producing a unique energy-conservative regulating power supply will be evident as this description proceeds.